siRNA against caveolin-1 inhibited effect of CD26 on CD86 up-regulation in TT-loaded monocytes. (A) CD86 expression of caveolin-1 knock-down monocytes was not increased by CD26 stimulation. Data represent mean ± SE of five independent experiments. **, points of no significant change by sense siRNA. * and ***, points of significant increase. MFI, mean fluorescence intensity; SS1, sense 1; SS2, sense 2; mis, mismatched. (B) Purified monocytes were transfected with or without siRNA, followed by treatment with TT. After pulse with rsCD26, the preincubated monocytes were incubated with purified T cells from the same donor. Proliferation of T cells was monitored by measuring BrdUrd (BrdU) incorporation by ELISA. The degree of proliferation is indicated at OD450 with reference at OD690. The experiments represent mean values ± SE calculated from five independently performed experiments each from different donors. N.S., points of no significant change by mismatched siRNA. *, **, and ***, points of significant increase.